Development of photographic emulsions



Patented Nov .5, 1946 N'l F PHOTOGBAPHIC EMULSIONS seheufing s. Fierke and Cyril J. Stand, Rochester, N. Y., assi'gnors to Eastman Kodak Company, Rochester, N. Y., a corporation of New DEVELOP Jersey I No Drawing.

4 This invention relates'to photography and particularly to a method for the dry processing of photographic emulsions. In Yackel, Leermakers and Stand U. S. ap plication Serial No. 500,924, filed concurrently herewith, a process isdescribed of developing photographic emulsions containing developing agents, by the application of vapors of ammonia graphic emulsions containing developing agents without the use of special apparatus. A further object is to provide a method for developing exposed photographic emulsions without the appli-: cation of alkaline vapors. A still further object is to provide a novel photographic material which may be processed conveniently by diy develop- Application September 2, 1943, Serial No. 500,923

8 Claims. (01. 95'88) ment. Other objects will appear from the following description of our invention.

These objects are accomplished, according to the'broader aspects of our invention, by incorporating in a silver halide emulsion a photo graphic developing agent and a nitrogen compound capable of generating an amine, and treating the exposed photographic material with steam or water vapor. This combination of ingredients produces a material which is suitable for-use in "dry processing of the emulsion, that is, processing without immersing the exposed photographic material in a liquid bath and, therefore, secures the advantages referred to in the Yackel, Leermakers and Stand application Seria1 No. 500,924. These advantages include the rapid development of the photographic material without resorting to long washing and drying p-amino-n-octane; These compounds are dis- Guanidine carbonate be solu-ble or insoluble in water. The water-solvent-such as butyl phthalate, ethyl sebacate, tri- 2 x 7 reaction with other compounds. The amines or ammonia do not cause development of the emulsion in the dry state but, in the presence of water, development of theexposed emulsion is brought about. In-the case of ammonia there is sometimes sufficient water in the coated emulsion to effect development but generally with the amines which are not decomposed to form ammonia, water must-beadded to effect development. Development can, therefore, be accomplished by the application to the exposed material of steam or water vapor.

The amines incorporated in the emulsion may uble amines may be added directly to the emulsion but the water-insoluble compounds are preferabiy dissolved in a water-insoluble, water-permeable solvent which is then dispersed in the emulsion. When incorporated in this way, the water-insoluble amines do not react on the silver halide until they are released by the action of the steam andthe emulsion "may, therefore, have a greater speed than when the water-soluble amines are incorporated directly in the emulsion. When the emulsion is acted on by steam, the amine is released from the solvent by what amounts to steam distillation, and thereby increases thealkalinity of the emulsion to the point where development of the layer is produced.

Water-insoluble amines which may be employed according toiour invention, include diisoamylamine, n-heptylamine, benzylamine and solved in a water-insoluble, water-permeable solo-cresyl phosphate, n-amylsuccinate, butyl benzoate or isoamylsulfone. Other water-insoluble, water-permeable materials such as those referred to on pages 2 and 3 of Jelleyand' Vittum U. S. Patent 2,322,027, grant-ed June 15, 1943, may be Guanidine hydrochloride Guanidine laurate Guanine hydrochloride v 2-amino-2-ethyl-propanediol For-mamide Adenine sulfate Hexamethylenetetramine Urea The following com monia or amines on heating or by reaction with other compounds, may be employed; the reaction by which the ammonia or amines are produced exposed. areas.

unds, which generate ambeing indicated below. While these are the reactions indicated in chemical textbooks, it is improbable that these are the only products produced under the conditions of our invention.

Betalnas I A JQNCECEOO; Mom 11- GH CHGOdI Ton-amethyiammonium iodide o The following examples illustrate methods of preparing emulsions according to our invention:

Example 1 T0 200 cc. ofv a gelatino-silver bromoiodide emulsion there are added the following ingredients:

! Cc. Chrome alum (5.5% solution) 9 2 (p dimethylaminophenyliminomethyl) benzothiazole ethoethylsulfate (desensitizer) (0.1% solution) i1 Hydroquinone solution) 3 Sodium sulilte (10% solution) 1.5 Soap bark extract 16 Dispersion of p-amino-n-octane 10 The dispersion of p-amino-n-octane is prepared bymixing'the following ingredients:

p-Amino-n-octane "cubic centimeters..- 5 Ethyl sebaca do Gelatin(10% solution) do 65 Water do 60 Alkanol B grams 1 This mixture is passed five times through a colloid mill to effect a dispersion of the ethyl sebacate containing the amine in the gelatin solution.

The emulsion was coated on a suitable support such as paper, glass or film, exposed to light and then heated for three minutes in a stream of steam and dried on a hot plate at moderate temperature for about one minute. This gave a very good image with little development outside the s Example 2 An emulsion was prepared in the same manner as described in Example 1, using a dispersion of n-heptylamine instead of a dispersion of fi-aminon-octane, the n-heptylamine being incorporated in the dispersion in an amount of 5 cc. and 10 ccof the dispersion emulsion.

Example 3 -An emulsion containing a water-soluble amine was prepared as follows:

, To 200 cc. ofgelatino-silverhalide emulsion there was added the following solution:

Chrome alum (5.5% solution) -4.-- 9 2 (p dimethylaminophenyliminomethyl) benzothiazole ethoe'thyls'ulfate 11 Hydroquinone in methyl alcohol (10% solution) Sodium sulflte (10% solution) 1.5 Urea (10% solution) 10 Example 4 An emulsion containing a water-soluble was prepared by adding to 200 cc. of a gelatinosilver halide emulsion. the following solution:

- Cc. Chrome alum (5.5% solution) 9 2 (p dimethylaminophenyliminomethyl) benzothiazole ethoethylsulfate (0.1% 80111? tion) Hydroquinone in methyl tion Sodium suliite (10% solution) 1.5 Guanine hydrochloride (10% solution) 10 After adding this mixture to the emulsion, the emulsion was adjusted to pH 6 before coating.

alcohol (10% solu- While development with steamqas described above produces a satisfactory photographic J image, the image thus produced is not permanent.

Development proceeds slowly upon exposure of the steam developed image to artificial light and more rapidly upon exposure to sunlight. This is caused by gradual development of the residual silver halide by the developing agent remaining in the emulsion and maybe overcome by treatment of the steam developed material with acid vapors or with an iodizing material. The following procedures are available.

vapors of an acidsuch as hydrochloric acid.

2. The residual silver halide may be iodized by bathing the developed material for one to two minutes in a 10% solution of potassium iodide or in a. 10% potassium iodide. solution containing 3% of sodium bisulflte. This prevents further development even in direct sunlight by converting the silver halide to silver iodide.

3. The silver halide may be iodized by incorporating in the dispersion of the amine or in the emulsion a dispersion of an alhl or cry] iodide. n-Butyl, ethyl, secondary butyl, tertiary butyl or other alkyl iodide may be used to iodize the residual silver halide. The iodides vary in their reactivity and a wide choice is available. ,The

dispersion of iodide need not be incorporated directly in the emulsion but may be coated over or under the emulsion layer. Upon heating with steam, the iodide is driven out of the dispersed particles and reacts with the silver halide. The

dispersion of the iodide may be made as follows:

n-Butyl iodide ams" 10- Butyl phthalate (In 20 Gelatin (10% solution) cubic centimeters- 40 Water do 30 Alkanol B ams-.. 0.3

This mixture is passed three times through a colloid mill in order to efiect a dispersion of the 7 iodide and butyl phthalate in the gelatin. 7

being added to 200cc. of-

1. The developed material may be treated with V sequent reaction with silver halide is thus delayed until after the development has been completed.

4. The iodide may be introduced in the steam after development. For example, after exposure and developmentby steam as described above, an alcoholic solution of iodide is introduced in the steam to eifect a conversion of the silver halide to silver iodide. A fairly active organic iodide such as tertiary butyl iodide or allyl iodide may beused for this purpose. However, since these compounds are quite unstable, a more convenient compoun is hexamethylenetetramine allyl iodide or other quaternary ammohium salt of such active iodide. This allows easier handling of the material and injurious by-products such as hydriodic acid or iodine which would oxidize the developed image are less likely to be present. After treatment with volatile iodides in this way, the print is dried quickly, for example, on a hot plate as described above.

Our process of development is useful in the production of copies of line drawings where a number of copies are needed in a minimum of time or where the copies need not be stable over long periods of time. The advantage of using steam to introduce the moisture necessary for development is that the paper base or other support does not become wet during processing, washing is eliminated and drying is accomplished in a few seconds.

a silver halide developing agent and an excess of an ammonia-generating organic compound. which comprises subjecting said exposed layer to the action of steam for a sumcient length of time to generate ammonia from said organic compound and to produce a visible image in said I layer and then treating the layer with acid vapors for a, short period of time.

4. The method of developing an exposed gelatino-silver halide emulsion layer containing a silver halide developing agent and an excess of an ammonia-generating organic compound, which comprises subjecting said exposed layer to the action of steam for a suflicient length of time to generate ammonia from said organic compound and to produce a visible image in said layer and then iodizing the undeveloped silver halide in the layer.

5. The method of developing an exposed gelatino-silver halide emulsion layer containing a silver halide developing agent and an excess of an ammonia-generating organic compound, which 4 comprises subjecting said exposed layer to the It will be understood that the modifications '1. The method of developing an exposed silver halide layer containing a photographic developing agent and an excess of an organic nitrogen compound capable of generating a volatile amine upon application of steam, which comprises subjecting said exposed'layer to the action 01' steam.

2. The method of developing an exposed gelatino-silver halide emulsion layer containing a, silver halide developing agent and an excess of an ammonia-generating organic compound, which comprises subjecting said exposed layer to the action of steam for a sumcient length of time to generate ammonia from said organic compound and to produce a. visible image in said layer.

3. The method of developing an exposed action of steam for a sufiicient length of time to generate ammonia from said organic compound and to produce a visible image in said layer, and then treating said layer with vapors of a volatile iodide to convert the remaining silver halide to silver iodide.

6. A photographic emulsion capable of being developed by the application of steam only, comprising a gelatino-silver halide emulsion containing a photographic developing agent and having dispersed therein particles of a water-insoluble, water-permeable liquid containing a water-insoluble amine capable of generating a volatile amine an thereby increasing the alkalinity of the emulsion upon application of steam to the emulsion.

7. The method of forming a silver image in a silver halide emulsion layer without immersing said layer in a liquid, which comprises incorporating in a slow silver halide emulsion a silver halide developing agent, and an organic nitrogen com-' pound capable of generating a volatile amine upon application of steam, coating said emulsion on a support, exposin said emulsion to light. and subjecting said exposed emulsion to the action of steam to produce a silver image therein.

8. The method of forming a silver image in a silver halide emulsion layer without immersing said layer in a liquid, which comprises incorporating in a silver halide emulsion a silver halide developing agent, a desensitizer, and an organic nitrogen compound capable of generating a sion to the action of steam to produce a silver gelatino-silver halide emulsionlayer containing image therein.

. SCHE'URING S. CYRIL J.- STAUD. 

